The end of the midterm primary season is nigh , and Tuesday marks the penultimate date of intra-party brawls this cycle.

Most notably, Rep. Ann Kirkptrick, D-Ariz., will at last her learn her general election rival as 1st District's GOP voters pick a nominee in this competitive race. To the west, suburban Phoenix Republicans will nominate their challenger to freshman Democratic Rep. Kyrsten Sinema.

Another pair of House contests in Arizona and Oklahoma will almost certainly pick future House members in districts with highly partisan voting populations. EMILY's List and a GOP effort to help female candidates also have skin in these contests.

Florida polls close at 7 p.m. EST, while Oklahoma's close at 8 p.m. EST. Arizona latest polls close out the night at 10 p.m. EST. Check out Roll Call's "At the Races " blog for live results as soon as the first polls close.

Here are the four things to watch on Tuesday evening:

1. Which Republican will Kirkpatrick face this fall? The National Republican Congressional Committee Chairman has targeted Arizona's 1st District with vigor. But Washington, D.C., operatives are increasingly grim about this seat because all three GOP contenders have proven flawed.

Public polling for the primary shows inconsistent results. But the self-described business-friendly wing of the party — Main Street Advocacy and the U.S. Chamber of Commerce — are putting radio and television money behind state Speaker Andy Tobin's candidacy. Still, even if he does prevail, most observers agree he ran a poor primary race and his campaign is in weak financial shape. The legislative district of Tobin's rival, state Rep. Adam Kwasman, covers a conservative stronghold. But he earned national headlines earlier in the summer when he misidentified children riding on a bus to YMCA camp for migrant minors. Finally, there's rancher Gary Kiehne, a candidate whose greatest strength is his self-funding capacity. But over the course of the primary, Kiehne repeatedlyracked upoff-color comments that would keep national Republicans up at night if he's the nominee.

The GOP's candidate conundrum in this sprawling, eastern Arizona district is even more frustrating for national Republicans because Mitt Romney carried it by two points. The race is rated Tilts Democrat by the Rothenberg Political Report/Roll Call.

But national Democrats are holding off on the gloating, arguing the district is such difficult terrain that Kirkpatrick could lose to nearly anyone, especially if the national landscape doesn't favor Democrats.

2. Who will take on Sinema in the fall? Retired Air Force Lt. Col. Wendy Rogers faces former Arizona State University quarterback Andrew Walter for the honors of challenging Sinema, a freshman Democrat, in November.

Like the 1st District, Republicans are similarly pessimistic about their prospects here. What's more, the region's dominant newspaper isn't a fan of either, declining to endorse in the primary.

Rogers is a participant in Project GROW , a national Republican effort to help female candidates, including in primaries. But Rogers has made some inflammatory comments during her previous House bid, which made many Republicans give Walter a second look.

Sinema has spent her freshman term building up a massive war chest and tacking to the center of this competitive district east of Phoenix. Republicans on Capitol Hill have started to view the race as less about November, and more about weaking Sinema for a stronger challenger in 2016.

Arizona's 9th District is rated Democrat Favored by the Rothenberg Political Report/Roll Call.

3. Who are the new all-but-certain new members of Congress? Two races — a primary in Arizona and a runoff in Oklahoma — will all but determine the next member hailing from these open seats.

In Oklahoma's 5th District, former state Sen. Steve Russell and State Corporation Commissioner Patrice Douglas face off to replace GOP Rep. James Lankford. The two-term congressman won the GOP primary for Senate in June and will most likely succeed Sen. Tom Coburn, R-Okla., who will resign from Congress later this year.

Also in the June primary, Russell edged Douglas, 27 percent to 24 percent — a margin of less than 1,000 votes. Since neither candidate reached the 50 percent threshold in the primary, Douglas and Russell must face each other again on Tuesday.

Russell, a retired lieutenant colonel in the Army, has played up his military service in the race. He commanded the operation that captured Saddam Hussein in Iraq in 2003. Douglas has received a boost from some of the House Republican women, as well as business groups like the Chamber of Commerce.

Whomever emerges from the primary will almost certainly be the next member of Congress from this Safe Republican district that Romney carried with 59 percent in 2012.

Back in Arizona, Democrats anticipated a brawl in the race to replace retiring Democratic Rep. Ed Pastor. Former state Rep. Ruben Gallego and former Maricopa County Supervisor Mary Rose Wilcox did not disappoint .

A longtime local official, Wilcox has decades' worth of name recognition, the backing of EMILY's List and Pastor's endorsement. But the betting money is on Gallego's better-organized effort.

Arizona's 7th District is rated Safe Democratic by the Rothenberg Political Report/Roll Call.

4. Will there be any surprises in Florida? All seems to be quiet in Florida on Tuesday, especially in the wake of a judge approving small changes to the state's congressional map for 2016.

Miami Dade School Board Member Carlos Curbelo is expected to cruise to the nomination to face Democratic Rep. Joe Garcia for Florida's 26th District in the fall. In the 18th District, former state Rep. Carl Domino is the best bet to win the GOP nod to take on Democratic Rep. Patrick Murphy.